Thanks in advance for the help.

I'm working on a friends 89 Bronco 302 automatic. He has let it set for about 4 years and decided he want to get it back on the road and brought it to me.

I replaced all the brakes, including calipers, rear wheel cylinders and repack front wheel bearings. Changed Oil and filter and tranny oil and filter.

When I got all this done I started on his alternator problems. The plug was messed up. So I replaced it. Started it up and still wouldn't charge. Took the alternator off and let him take it to have it tested, it was bad and he brought me a new on. I put it on and started it up. Gage did show charge, then I heard something pop and smoke started coming out from under the hood. I shut it off and found a wire going into the main wiring harness had burnt. Replaced the burnt piece of wire, may have been a fuse link cause it was smaller than the wires it was spliced to, it looked factory and there are other wires in the same area that have the same set up. Anyway I spliced in a wire that was slightly heaver than the original wire. Now that wire doesn't over heat but the PK/BK wire that goes to the fuel pump inertia switch is over heating. matter of fact it burnt the plug up. The wire over by the battery which was the one I spliced in a new wire is a yellow wire.

Any suggestions on how to find the short and where to look. I've thought about splicing in a wire from where the original problem was and going straight to the fuel pump relay to see if that solves the problem.

And since that happened the new rebuilt alternator will not charge either. Is there somewhere in the wiring harness where the charging wiring and the fuel pump wiring connects?

This has really got me stumped. Truck starts and runs fine. It is hard to start, you have to cycle the key three or four times to build up fuel pressure then it will start right up. Which tells me it probably needs one or both pumps replaced. Ready to get this out of my garage.

Thanks again,
Delos

 

Sounds like one of the pumps may be shorted causing the overheating problem in the wiring. A failed pump motor can easily cause an overload in the circuit especially if the armature is locked up. Furthermore, a short of that magnitude assuming fusible links or fuses have been removed or replaced with capacities larger than they should be could definitely fry a diode or the voltage regulator in the alternator.

 

Never really had any problems before to have to mess with the fuseable links. Are they just a smaller gauge wire?

How would I determine whether it was the high pressure pump or the low pressure pump?


Thanks for the response
Delos

 

If you haven't replaced fusible links or rewired with a different size wire, a stalled pump motor is the most likely culprit. I wouldn't worry that you have any other wiring issues until you can determine whether one of the pumps is stalled. If the problem is indeed one of the pumps you should be able to follow the wiring back to each pump and the one with the extra warm wiring or pump body is the most likely culprit. The fact that it takes a few cycles of the key to get things "flowing" I would suspect the low pressure pump because the high pressure unit will prime even without the low pressure unit running but it takes a long time to draw fuel that far forward from the tank to the middle of the truck which is where the high pressure unit is mounted on the frame rail.